i have a problem maybe u can help me. the right side plugseems to get carbon fouled and if clean it off and reuse it . it seems to run ok other than that. i have adjusted the distributor thinking it might just have to be reset but now it runs ok but backfires and still fouls the right plug maybe running to rich if so how do i adjust that. is there a general {safe} position for the disributor to be between the the pry hole on the distributor plate any help would be great thank you